So, this is a question that certainly has a caveat – Can Allergies Make Just One Eye Red?. Why you ask? Well, the shorter answer is that if you have an allergy then you have an allergy and it’s will affect all parts of your body equally.
What I mean is, if you have hay fever, for example, the pollen won’t just affect one eye, it will affect both eyes. If pollen gets into your system, into your eyes, then they will itch.
Let me quote something from MedicineNet.com
The scenario for developing allergy symptoms and signs is much the same for the eyes as that for the nose. Allergens cause the allergy antibody IgE to coat numerous mast cells in the conjunctiva. Upon reexposure to the allergen, the mast cell is prompted to release histamine and other mediators. The result is itching, burning, and runny eyes that become red and irritated due to inflammation, which results in congestion and discomfort.
But here’s the caveat…
However, the question does say just one eye red and this is certainly something that can happen from my experience. Let me explain a little more.
So, from my own experience, my eyes can go itchy and red if the pollen gets too bad. However, I often find that one eye may get itchier than the other and I find that that one eye goes red while the other one doesn’t.
Rubbing could also be a factor if you rub one eye and not the other.
So, you see – the truth is that the allergy does affect both eyes, but from my experience, you can get one eye go red while the other remains normal.
However, I have also found in the past that I will have one eye go red, then a little time later the other eye will also go red. The redness in one eye is only for a short while.
The answer to this question is certainly not a simple one for sure. It’s both a Yes and a No. I think that you should not worry if you see just one eye go red as this could happen – it really does depend on how much of the allergen is in that eye compared to the other.